Polymer nanomaterials with fascinating physicochemical properties that differ from their bulk states have gained extensive attention in recent years. To develop polymer nanomaterials with distinctive functionalities, critical issues such as chain alignments and micro-phase separation of polymers under nanoconfinement should be thoroughly discussed.

The previous works, however, focus mainly on the confined crystallization behaviors of conventional polymers. Confined polymers with more complicated organization systems, such as stereocomplex PMMA, have yet to be discussed. Recently, Prof. Jun-Tai Chen’s research group from National Yang Ming Chiao Tung University has reported the study of self-assembly and crystallization behavior of the stereocomplex PMMA under nanoconfinement. The polymer is first introduced into the nanopores of the metal oxide templates by the solution wetting method to prepare the polymer nanorods. The thermal properties and crystal structures of the polymer are identified by differential scanning calorimetry and grazing-incidence small-angle X-ray scattering (GIWAXS), respectively. This study is also conducted by the light source from the National Synchrotron Radiation Research Center to investigate the weak diffraction signal of the polymer inside the nanopores.

Polymers confined in narrow three-dimensional geometries bring exciting opportunities for the development of functional materials, such as dynamic photoswitches and environment-responsive electronics. Over the years, researchers have demonstrated that the light-driven isomerization or molecular conformation of small molecules can turn into macroscopic property changes and provide multiple applications, such as solid-to-liquid transitions, live-cell imaging, and conductance photoswitching. Due to the difficulties of complicated synthetic routes and problematic side effects, however, only a few reports have achieved the photocontrolled ionic conductivities in the solid state.

In another recent work reported by Prof. Jun-Tai Chen’s research group, a newly photoswitchable composite gel polymer electrolyte consisting of photochromic spiropyran molecules and nanoporous anodic aluminum oxide is demonstrated. The spiropyran as the thermodynamically stable form can isomerize to the open merocyanine form upon UV (365 nm) irradiation and reversibly isomerize back to the spiropyran form upon visible (555 nm) light irradiation. Taking the advantage of the light-induced surface property changes, they successfully control the ion mobility at the interfaces.

The researches have been published by Macromolecules and Chemistry—A European Journal. Additionally, one of the publications has been selected as the cover story. The authors would like to acknowledge the supports from the Ministry of Science and Technology of Taiwan and the Center for Emergent Functional Matter Science of National Yang Ming Chiao Tung University.